FreeBSD/Linux Kernel Cross Reference
sys/contrib/device-tree/Bindings/gpio/gpio-eic-sprd.txt

     Spreadtrum EIC controller bindings
     
     The EIC is the abbreviation of external interrupt controller, which can
     be used only in input mode. The Spreadtrum platform has 2 EIC controllers,
     one is in digital chip, and another one is in PMIC. The digital chip EIC
     controller contains 4 sub-modules: EIC-debounce, EIC-latch, EIC-async and
     EIC-sync. But the PMIC EIC controller contains only one EIC-debounce sub-
     module.
     
    The EIC-debounce sub-module provides up to 8 source input signal
    connections. A debounce mechanism is used to capture the input signals'
    stable status (millisecond resolution) and a single-trigger mechanism
    is introduced into this sub-module to enhance the input event detection
    reliability. In addition, this sub-module's clock can be shut off
    automatically to reduce power dissipation. Moreover the debounce range
    is from 1ms to 4s with a step size of 1ms. The input signal will be
    ignored if it is asserted for less than 1 ms.
    
    The EIC-latch sub-module is used to latch some special power down signals
    and generate interrupts, since the EIC-latch does not depend on the APB
    clock to capture signals.
    
    The EIC-async sub-module uses a 32kHz clock to capture the short signals
    (microsecond resolution) to generate interrupts by level or edge trigger.
    
    The EIC-sync is similar with GPIO's input function, which is a synchronized
    signal input register. It can generate interrupts by level or edge trigger
    when detecting input signals.
    
    Required properties:
    - compatible: Should be one of the following:
      "sprd,sc9860-eic-debounce",
      "sprd,sc9860-eic-latch",
      "sprd,sc9860-eic-async",
      "sprd,sc9860-eic-sync",
      "sprd,sc2731-eic".
    - reg: Define the base and range of the I/O address space containing
      the GPIO controller registers.
    - gpio-controller: Marks the device node as a GPIO controller.
    - #gpio-cells: Should be <2>. The first cell is the gpio number and
      the second cell is used to specify optional parameters.
    - interrupt-controller: Marks the device node as an interrupt controller.
    - #interrupt-cells: Should be <2>. Specifies the number of cells needed
      to encode interrupt source.
    - interrupts: Should be the port interrupt shared by all the gpios.
    
    Example:
            eic_debounce: gpio@40210000 {
                    compatible = "sprd,sc9860-eic-debounce";
                    reg = <0 0x40210000 0 0x80>;
                    gpio-controller;
                    #gpio-cells = <2>;
                    interrupt-controller;
                    #interrupt-cells = <2>;
                    interrupts = <GIC_SPI 52 IRQ_TYPE_LEVEL_HIGH>;
            };
    
            eic_latch: gpio@40210080 {
                    compatible = "sprd,sc9860-eic-latch";
                    reg = <0 0x40210080 0 0x20>;
                    gpio-controller;
                    #gpio-cells = <2>;
                    interrupt-controller;
                    #interrupt-cells = <2>;
                    interrupts = <GIC_SPI 52 IRQ_TYPE_LEVEL_HIGH>;
            };
    
            eic_async: gpio@402100a0 {
                    compatible = "sprd,sc9860-eic-async";
                    reg = <0 0x402100a0 0 0x20>;
                    gpio-controller;
                    #gpio-cells = <2>;
                    interrupt-controller;
                    #interrupt-cells = <2>;
                    interrupts = <GIC_SPI 52 IRQ_TYPE_LEVEL_HIGH>;
            };
    
            eic_sync: gpio@402100c0 {
                    compatible = "sprd,sc9860-eic-sync";
                    reg = <0 0x402100c0 0 0x20>;
                    gpio-controller;
                    #gpio-cells = <2>;
                    interrupt-controller;
                    #interrupt-cells = <2>;
                    interrupts = <GIC_SPI 52 IRQ_TYPE_LEVEL_HIGH>;
            };
    
            pmic_eic: gpio@300 {
                    compatible = "sprd,sc2731-eic";
                    reg = <0x300>;
                    interrupt-parent = <&sc2731_pmic>;
                    interrupts = <5 IRQ_TYPE_LEVEL_HIGH>;
                    gpio-controller;
                    #gpio-cells = <2>;
                    interrupt-controller;
                    #interrupt-cells = <2>;
            };

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